South Korea is expressing doubt that a second round of multilateral talks on North Korea's nuclear weapons programs will be held this month. The comments come a day before an expected visit to the North by U.S. congressional aides and nuclear weapons experts.

South Korean officials say a new round of six-party talks on resolving the North Korean nuclear standoff will probably not take place in January.

South Korean National Security Adviser Ra Jong-il said Monday that the talks are unlikely because of the Chinese Lunar New Year and the Russian Christmas holidays this month.

China and Russia, along with the United States, Japan and South Korea, held an initial round of talks with North Korea last August about halting its nuclear programs. The talks made little progress and since then, diplomats have tried to arrange another meeting. However, Mr. Ra says he remains hopeful that more talks will take place.

While diplomats try to arrange more talks, two U.S. delegations are going to North Korea this week. Two groups of academics, scientists and congressional aides were invited by the isolated Stalinist state to visit its main Yongbyon nuclear facility. They will be the first outside experts to visit the site since North Korea threw out United Nations monitors a year ago.

The delegations are unofficial and do not represent the Bush administration. But Lee Nae-young, associate professor of political science at Korea University in Seoul, says the visits might signal that North Korea is willing to end its nuclear ambitions.

"It is a sign to indicate North Korea is willing to change their previous position and they want to have more cooperative relations with the United States and foreign countries," he says. "So I think it is a good sign."

But North Korea on Monday suggested that the next move was up to Washington. An editorial in the state-run Rodong Sinmun newspaper says Pyongyang is ready to resume the international dialogue if Washington and its allies first agree to concessions.

North Korea has made similar demands in the past -- it wants economic aid and a security guarantee before it will freeze its nuclear programs. U.S. officials have rejected that stance, saying Pyongyang must first verifiably dismantle its weapons program.

The crisis flared in October 2002, when Washington says Pyongyang admitted to running a nuclear program in defiance of international conventions.